Liquid crystal medium, optical device, and liquid crystal compound

Abstract

A liquid crystal medium having stability to heat, light and so forth, a wide liquid crystal phase temperature range, a low driving voltage and a small permittivity and exhibiting an optically isotropic liquid crystal phase is described. An optical device or the like having a short response time, a large contrast ratio, a low driving voltage and a small permittivity is also described. The liquid crystal composition contains an achiral component (T) and a chiral agent, and exhibits an optically isotropic liquid crystal phase. The achiral component (T) includes at least one compound represented by formula (1): wherein, for example, R 1 is alkyl having 1 to 12 carbons, A 1 and A 2 are 1,4-phenylene, Z 1 and Z 2 are single bonds, Z 3 is —COO— or —CF 2 O—, L 11 is hydrogen, fluorine or chlorine, Y 1 is fluorine, chlorine, —CF 3 or —OCF 3 , n1 and n2 are each independently 0 or 1, and n1+n2≧1.

What is claimed is: 
     
       1. A liquid crystal composition, containing an achiral component (T) and a chiral agent (K), and exhibiting an optically isotropic liquid crystal phase, wherein the achiral component (T) comprises, as a first component, at least one compound (1) represented by formula (1), 
       
         
           
           
               
               
           
         
       
       wherein in formula (1),
 R 1  is hydrogen, alkyl having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkynyl having 2 to 12 carbons, or alkoxy having 1 to 11 carbons; 
 A 1  is independently 1,3-dioxane-2,5-diyl, 1,4-phenylene, 3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene or 3-fluoro-5-chloro-1,4-phenylene; 
 Z 1  is independently a single bond, or alkylene having 1 to 4 carbons; 
 Z 3  is —CF 2 O—; 
 L 11  is hydrogen or fluorine; 
 Y 1  is fluorine, —CF 3  or —OCF 3 ; and 
 n1 is 1; 
 
       wherein the chiral agent (K) comprises, as a chiral component, at least one compound (K6-6) represented by formula (K6-6), 
       
         
           
           
               
               
           
         
       
       wherein in formula (K6-6), each R K  is independently alkyl having 3 to 10 carbons. 
     
     
       2. The liquid crystal composition of  claim 1 , wherein the achiral component (T) comprises at least one compound represented by any one of formulae (1-1) or (1-3), 
       
         
           
           
               
               
           
         
       
       wherein in formulae (1-1) or (1-3),
 R 1A  is alkyl having 1 to 12 carbons or alkenyl having 2 to 12 carbons; 
 Z 1  is independently a single bond, or alkylene having 1 to 4 carbons; 
 Y 1A  is fluorine, —OCF 3  or —CF 3 ; and 
 (F) is fluorine or hydrogen. 
 
     
     
       3. The liquid crystal composition according to  claim 1 , further comprising, as a second component of the achiral component (T), at least one selected from the group consisting of a compound (3) represented by formula (3) and a compound (7) represented by formula (7), 
       
         
           
           
               
               
           
         
       
       wherein in formula (3),
 R 3  is hydrogen, or alkyl having 1 to 12 carbons, wherein at least one —CH 2 — in R 3  is optionally replaced with —O—, —S—, —COO— or —OCO—, at least one —CH 2 —CH 2 — in R 3  is optionally replaced with —CH═CH—, —CF═CF— or —C≡C—, at least one hydrogen in R 3  is optionally replaced with fluorine or chlorine, and in R 3 , —O— and —CH═CH— are not adjacent to each other and —CO— and —CH═CH— are not adjacent to each other; 
 Z 31 , Z 32 , Z 33  and Z 34  are each independently a single bond, or alkylene having 1 to 4 carbons, wherein at least one —CH 2 — in the alkylene is optionally replaced with —O—, —COO— or —CF 2 O—; 
 L 31 , L 32 , L 33 , L 34 , L 35  and L 36  are each independently hydrogen or fluorine; 
 X 3  is hydrogen, halogen, —SF 5 , or alkyl having 1 to 10 carbons, wherein at least one —CH 2 — in X 3  is optionally replaced with —O—, —S—, —COO— or —OCO—, at least one —CH 2 —CH 2 — in X 3  is optionally replaced with —CH═CH—, —CF═CF— or —C≡C—, at least one hydrogen in X 3  is optionally replaced with fluorine or chlorine, and in X 3 , —O— and —CH═CH— are not adjacent to each other and —CO— and —CH═CH— are not adjacent to each other; 
 n31 and n32 are each independently 0 or 1; and 
 when Z 33  is —CF 2 O— or —COO—, Z 34  is a single bond and L 34  is fluorine, both L 35  and L 36  are fluorine; 
 
       
         
           
           
               
               
           
         
       
       and in formula (7),
 R 7  is hydrogen, or alkyl having 1 to 12 carbons, wherein at least one —CH 2 — in R 7  is optionally replaced with —O—, —S—, —COO— or —OCO—, at least one —CH 2 —CH 2 — in R 7  is optionally replaced with —CH═CH—, —CF═CF— or —C≡C—, at least one hydrogen in R 7  is optionally replaced with fluorine or chlorine, and in R 7 , —O— and —CH═CH— are not adjacent to each other and —CO— and —CH═CH— are not adjacent to each other; 
 L 71 , L 72 , L 73 , L 74 , L 75 , L 76 , L 77  and L 78  are each independently hydrogen or fluorine; 
 Z 71 , Z 72  and Z 73  are each independently a single bond, —COO— or —CF 2 O—; 
 X 7  is hydrogen, halogen, —SF 5 , or alkyl having 1 to 10 carbons, wherein at least one —CH 2 — in X 7  is optionally replaced with —O—, —S—, —COO— or —OCO—, at least one —CH 2 —CH 2 — in X 7  is optionally replaced with —CH═CH—, —CF═CF— or —C≡C—, at least one hydrogen in X 7  is optionally replaced with fluorine or chlorine, and in X 7 , —O— and —CH═CH— are not adjacent to each other and —CO— and —CH═CH— are not adjacent to each other; 
 n71 is 0 or 1; 
 when n71=1, Z 72  is —CF 2 O— or —COO—, Z 73  is a single bond, and both L 75  and L 76  are fluorine, both L 77  and L 78  are fluorine; and 
 when n71=0, Z 71  is —CF 2 O— or —COO—, Z 73  is a single bond, and both L 75  and L 76  are fluorine, both L 77  and L 78  are fluorine. 
 
     
     
       4. The liquid crystal composition of  claim 3 , wherein the compound (3) is a compound represented by any one of formulae (3-1) to (3-3), 
       
         
           
           
               
               
           
         
       
       wherein in formulae (3-1) to (3-3),
 each R 3A  is independently alkyl having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkoxy having 1 to 11 carbons; 
 L 31 , L 33 , L 34  and L 36  are each independently hydrogen or fluorine; and 
 X 3A  is fluorine, chlorine, —CF 3  or —OCF 3 . 
 
     
     
       5. The liquid crystal composition of  claim 3 , wherein the compound (7) is a compound represented by any one of formulae (7-1) to (7-8), 
       
         
           
           
               
               
           
         
       
       wherein in formulae (7-1) to (7-8),
 each R 7A  is independently hydrogen, alkyl having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkoxy having 1 to 11 carbons; 
 L 72 , L 74 , L 76 , L 77  and L 78  are each independently hydrogen or fluorine; 
 each X 7A  is independently fluorine, chlorine, —CF 3  or —OCF 3 ; 
 Z 71  and Z 72  are each independently a single bond, —COO— or —CF 2 O—, wherein at least one of Z 71  and Z 72  is —COO— or —CF 2 O—; and 
 when L 76  is fluorine, both L 77  and L 78  are fluorine. 
 
     
     
       6. The liquid crystal composition of  claim 3 , wherein the compound (7) is a compound represented by any one of formulae (7-2-1) to (7-2-7), 
       
         
           
           
               
               
           
         
       
       wherein in formulae (7-2-1) to (7-2-7),
 each R 7A  is independently alkyl having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkoxy having 1 to 11 carbons; and 
 X 7A  is fluorine, chlorine, —CF 3  or —OCF 3 . 
 
     
     
       7. The liquid crystal composition of  claim 3 , containing a total of 10 to 30 wt % of the compound (1), a total of 20 to 60 wt % of the compound (3) and a total of 30 to 70 wt % of the compound (7), based on a total weight of the achiral component (T). 
     
     
       8. The liquid crystal composition of  claim 3 , further comprising, as a third component of the achiral component (T), at least one selected from the group consisting of a compound (4) represented by formula (4) and a compound (2) represented by formula (2), 
       
         
           
           
               
               
           
         
       
       wherein in formula (4),
 R 4  is alkyl having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkoxy having 1 to 11 carbons; 
 B 41 , B 42  and B 43  are each independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene, 3,5-dichloro-1,4-phenylene or pyrimidine-2,5-diyl, wherein at least one of B 41 , B 42  and B 43  is 1,4-cyclohexylene, 1,4-phenylene or pyrimidine-2,5-diyl; 
 Z 41 , Z 42 , Z 43 and Z 44  are each independently a single bond, ethylene, —COO—, —OCO—, —CF 2 O— or —OCF 2—;    
 L 46 , L 47 , L 48  and L 49  are each independently hydrogen or fluorine; 
 X 4  is fluorine, chlorine, —CF 3  or —OCF 3 ; 
 n41 and n42 are each independently 0 or 1; and 
 when Z 43  is —CF 2 O— or —COO—, Z 44  is a single bond and both L 46  and L 47  are fluorine, both L 48  and L 49  are fluorine; 
 
       
         
           
           
               
               
           
         
       
       and in formula (2),
 R 2  is hydrogen, or alkyl having 1 to 12 carbons, wherein at least one —CH 2 — in R 2  is optionally replaced with —O—, —S—, —COO—, —OCO—, —CH═CH—, —CF═CF— or —C≡C—, at least one hydrogen in R 2  is optionally replaced with halogen, or alkyl having 1 to 3 carbons, and in R 2 , —O— and —CH═CH— are not adjacent to each other and —CO— and —CH═CH— are not adjacent to each other; 
 A 21 , A 22 , A 23  and A 24  are each independently 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, 1,4-phenylene, 1,4-phenylene in which one or two hydrogens are replaced with fluorine, 1,4-phenylene in which two hydrogens are replaced with fluorine and chlorine respectively, pyridine-2,5-diyl, or pyrimidine-2,5-diyl; 
 Z 21 , Z 22 , Z 23 , Z 24 , Z 25  and Z 26  are each independently a single bond, or alkylene having 1 to 4 carbons, wherein at least one —CH 2 — in the alkylene is optionally replaced with —O—, —COO— or —CF 2 O—; 
 L 21 , L 22  and L 23  are each independently hydrogen or fluorine; 
 X 2  is fluorine, chlorine, —CF 3  or —OCF 3 ; 
 n21, n22, n23 and n24 are each independently 0 or 1, and 1≦n21+n22+n23+n24 ≦2; and 
 when Z 26  is a single bond and L 21 is fluorine, both L 22  and L 23  are fluorine. 
 
     
     
       9. The liquid crystal composition of  claim 8 , wherein the compound (4) is a compound represented by any one of formulae (4-1) to (4-10), 
       
         
           
           
               
               
           
         
       
       wherein in formulae (4-1) to (4-10),
 each R 4A  is independently alkyl having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkoxy having 1 to 11 carbons; 
 X 4A  is fluorine, chlorine, —CF 3  or —OCF 3 ; and 
 L 40  to L 49  are each independently hydrogen or fluorine, wherein when both L 46  and L 47  are fluorine, both L 48  and L 49  are fluorine. 
 
     
     
       10. The liquid crystal composition of  claim 8 , wherein the compound (2) is a compound represented by any one of formulae (2-1-1-2), (2-1-2-1), (2-1-3-1), (2-1-3-2), (2-1-4-2) and (2-1-4-3), 
       
         
           
           
               
               
           
         
       
       wherein in formulae (2-1-1-2), (2-1-2-1), (2-1-3-1), (2-1-3-2), (2-1-4-2) and (2-1-4-3),
 each R 2A  is independently alkyl having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkoxy having 1 to 11 carbons; 
 each (F) is independently hydrogen or fluorine; and 
 X 2A  is fluorine, chlorine, —CF 3  or —OCF 3 . 
 
     
     
       11. The liquid crystal composition of  claim 1 , exhibiting a chiral nematic phase at any temperature in a range of −20 to 70° C., and having a helical pitch of 700 nm or less within at least a part of the temperature range. 
     
     
       12. A mixture, comprising the liquid crystal composition of  claim 1  and a polymerizable monomer. 
     
     
       13. A polymer/liquid-crystal composite material, obtained by polymerizing the mixture of  claim 12 , for use in a device driven in an optically isotropic liquid crystal phase. 
     
     
       14. An optical device, comprising two substrates in which electrodes are disposed on one or both thereof, a liquid crystal medium disposed between the substrates, and an electric field applying means for applying an electric field to the liquid crystal medium through the electrodes, wherein the liquid crystal medium is the liquid crystal composition of  claim 1 . 
     
     
       15. An optical device, comprising two substrates in which electrodes are disposed on one or both thereof, a liquid crystal medium disposed between the substrates, and an electric field applying means for applying an electric field to the liquid crystal medium through the electrodes, wherein the liquid crystal medium is the polymer/liquid-crystal composite material of  claim 13 .